Current clinical trends in total joint replacement (TJR) include implantation in younger patients and the use of non-cemented, porous coated metallic components which release greater amounts of corrosion products. In vitro and in vivo (animal and human) studies suggest a wide range of possible local and systemic biological sequelae to metallic release by TJRs. The proposed studies will address an important precursor to understanding the clinical significance of such effects: characterization of the release transport an storage of metallic moieties in patients with total hip replacements (THRs). This proposal involves three studies that will focus on distinct patient populations. The first study is a prospective, longitudinal study of metal ion release in patients undergoing primary THR with either a cementless titanium-base alloy prosthesis, a cementless cobalt-base alloy prosthesis or a cemented cobalt-base alloy prosthesis. The second study will examine metal ion release and local metal ion accumulation in patients undergoing revision THR for aseptic loosening of both cemented and cementless titanium-base alloy and cobalt-base alloy prosthesis. The third study will examine total body metal inventories in deceased individuals with cemented and cementless titanium-base alloy or cobalt-base alloy THRs. The primary analytical toll is Zeeman atomic absorption spectrophotometry (ZAAS). The results of theses studies will be critical in evaluating prospective risk to patients of the use of emerging total joint replacement technologies.